1. Field
Embodiments of the invention relate to the field of electric vehicle charging, and more specifically to managing electric current allocation between charging equipment for charging electric vehicles.
2. Background
Charging stations are typically used to provide charging points for electric vehicles (e.g., electric battery powered vehicles, gasoline/electric battery powered vehicle hybrid, etc.). Charging stations may be located in designated charging locations (e.g., similar to locations of gas stations), parking spaces (e.g., public parking spaces and/or private parking space), etc. Most electric plug-in vehicles have on board chargers that accept either 110V, 220V (230V in Europe) and draw power at current levels from 10 A to 70 A.
Electrical service (wiring and circuit protection) of the appropriate rating is typically brought to each of the charging stations. Multiple charging stations can be on the same electrical circuit, which is connected to an electrical breaker panel that is fed by a service drop from a local utility distribution transformer.
In a typical charging station installation, the size of the wiring, the breaker, and the service drop associated with a circuit is determined by simply summing the current ratings of each of the charging stations on the circuit (thus, a maximum use scenario is assumed). In this way, it can be assured that if all of the charging stations are in use at the same time, and all are delivering their maximum current, the breaker will not trip and the wiring will not overheat.